A front end of a mobile communication terminal device, e.g., a mobile phone, may be provided with a radio frequency switch (RF-SW) that may turn on and off radio frequency (RF). So far, the radio frequency switch has utilized compound-based (e.g., GaAs-based) field effect transistors (FETs) as its switching elements. But recently, FETs using SOI substrates have been also increasing (for example, refer to Non-patent Literature 1 and Non-patent Literature 2).